This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-49447 filed on Feb. 25, 2000.
1. Field of the Invention
The present invention relates to an electromagnetic valve working as a pressure regulating valve and an opening/closing valve suitable for use in an ORVR system.
2. Description of Related Art
A conventional vapor fuel treating system requires an ORVR (On Board Refueling Vapor Recovery) system shown in FIG. 7. In the ORVR system, vapor fuel arising in a fuel tank during fuel supply is not discharged to atmosphere, and a canister adsorbs the vapor fuel.
In the ORVR system shown in FIG. 7, pipes 202 and 205 connect a fuel tank 200 with a canister 210. A pressure sensor 201 is provided in the fuel tank 200 for detecting pressure inside the fuel tank 200. When a vapor fuel leak is detected, an electromagnetic valve 203 opens to allow the fuel tank 200 to communicate with the canister 210. An internal pressure valve 204 includes a diaphragm, and maintains the pressure inside the fuel tank 200 over a predetermined pressure. A fuel supply valve 206 includes a diaphragm. When the pressure inside the fuel tank 200 rises due to a fuel supply, the fuel supply valve 206 opens to discharge the vapor fuel into the canister 210 such that the canister 210 adsorbs the vapor fuel. When a purge valve 213 opens, an intake air passage 208 communicates with the canister 210.
In the conventional ORVR system in FIG. 7, there is need to prepare a lot of valves and pipes such as two pipes 202, 205 for connecting the fuel tank 200 with the canister 210, electromagnetic valve 203, internal pressure valve 204, and supply valve 206. Thus, an installation space for these parts is necessary, and the number of installations is increased.
An object of the present invention is to provide an electromagnetic valve working as pressure regulating valve and opening/closing valve, for reducing the number of parts.
According to a first aspect of the present invention, when a coil is not energized, a pressure-receiving member switches a communication between a first passage and a second passage due to pressure difference between a first pressure chamber and a second pressure chamber. That is, an electromagnetic valve works as a pressure regulating valve. When the coil is electrically energized, the first passage communicates with the second passage regardless the pressure difference between the first pressure chamber and the second pressure chamber. That is, the electromagnetic valve works as an electromagnetic opening/closing valve.
In this way, a single electromagnetic valve works as pressure regulating valve and opening/closing valve. Thus, the number of parts is reduced, so that the system is easily assembled. The system is compacted, so that the system is easily installed in a narrow space.
According to a second aspect of the present invention, a stator magnetically attracts the permanent magnet provided in the moving core. A communication between the first passage and the second passage is shut when the moving core is close to the stator. Thus, even when the magnetic force of the permanent magnet is small, sufficient force for closing valve is attained. Further, the coil is energized to generate a magnetic repelling force between the permanent magnet and the stator, so that the moving core leaves the stator. Since air gap between the moving core and the stator is small, even when the wind number of the coil is small, the electromagnetic valve can open, thereby compacting the electromagnetic valve.